User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/15.4 Safari/605.1.15
Steps to reproduce:
I ran a bunch of popular websites, scrolled up and down and tracked CPU and energy impact in Activity monitory for a variety of Mac browsers.
I tested Twitter, Amazon, Facebook, Udemy, Gmail and many other websites the results were always consistent.
This Reddit post shows others share the issue:
Firefox draws at least twice as much power for the same tasks as other browsers (according to Activity Monitor). While Chrome/Brave/Edge maybe max out at 10-20 on the energy impact panel... Firefox can sometimes hit 60. Not only that but Firefox can idle at worryingly high levels.
Even waving the mouse around Firefox window uses far more energy than waving it around Brave or Safari.
If I have a day of browsing, with Firefox my battery lasts maybe 6 hours, but if I use Chrome or Brave it lasts 10 hours. Keep in mind this involves a lot of idle time - if the browser was constantly in use the relative difference would be greater.
Is it possible it's a frame rate thing relating to the new 120hz screens? I do notice Firefox seems smoother than competition.
I'd expect the difference between browsers to not be this huge. It's a real shame for people like me who work undocked half the week and prefer Firefox. It's a deal breaker for me and many others.